Optical systems

ABSTRACT

A traffic signal apparatus for illuminating a message in alternate colors carries two light sources of different light color outputs. A one-way light mirror is positioned about one of the light sources to allow passage of light therefrom and to reflect substantially all light from an outside source such as the second light source. This optical system construction avoids unwanted light color reflection on a message plate of the housing during periods when the light source outside of the mirror is illuminated and the light source in the mirror is unlit.

[ 5] Mar. 7, 1972 FOREIGN PATENTS OR APPLICATIONS [54] OPTICAL SYSTEMSGreat Britain ......,..................340/107 [72] lnventor: Michael R.Cahlll, Bellerose, N.Y.

The Marbellte Company, Inc., NY.

Brooklyn,

[73] Assignee:

Primary Examiner-John W. Caldwell Assistant Examiner-J. Michael BobbittAttorney-Wolf, Greenfield & Sacks [22] Filed: July 15, 1970 211 Appl.No.: 55,060

ABSTRACT A traffic signal apparatus for illuminating a message in al-[52] US. Cl.,........,...........,.....340/ll0, 240/4649, 340/382,

' 350/97 temate colors carries two light sources of different lightcolor 3 1/ 0 outputs. A one-way light mirror is positioned about one ofthe .340/110, 106, 107, 382;

[5 l] Int.

[ Field of Search light sources to allow passage of light therefrom andto reflect 240/106, 46.49, 46.59, 41.35; 350/97, 2 substantially alllight from an outside source such as the second light source. Thisoptical system construction avoids References cued unwanted light colorreflection on a message plate of the housm .m m e m mu 6.5 r. .1 mm m Wmm mm F mm m. i wfi w hm m m D 8w w mm s E m l w 5. I. mm mm t 3 mm m mmm 77 00 11 ll 00 44 .3 M I P S "a E "t T "e A mu T. Cvk S 83 D BB m 300N 65 U mm 49 40 25 54 85 32 21- SIS il? PATENTEDHAR 1 I972.

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CONTROLLER FIG.5

- INVENTOR MICHAEL R. CAHILL BY 9/ ,WMd4Jaab ATTORNEYS FIG. 4

OPTICAL SYSTEMS BACKGROUND OF THE INVENTION In conventional trafficsignals such, as WALK-DON'T WALK signals, different colored lightsources are used in a single reflector to illuminate the WALK portion ofa message alone in one color at one time interval and sequentially toilluminate the DONT and the WALK message in a second color at a secondtime interval. This often requires the use of two light sources behind atransparent WALK message stencil plate such as an orange and a whiteincandescent lamp or bulb positioned behind a transparent WALK messagestencil plate.

When the orange lamp is illuminated, the WALK message appears orangesince conventional orange coatings on such lamps absorb all but thelight rays having the orange color wavelength and allow passage of onlythe orange light. However, a problem arises when the orange lamp is notilluminated and the white lamp is illuminated to cause the WALK messageto appear white. In this case, a portion of the white light which passesto the unlit orange lamp is altered in its color composin by theparticular reflective and absorptive properties of the orange coating ofthe unlit lamp causing an unwanted orange reflection to the WALKmessage. Thus, during illumination of the white lamp, the WALK messageis not entirely white but has an orange cast to at least certainportions of it. This orange cast is undesirable. Methods have beenproposed for eliminating the undesirable reflections but often involvecomplex optical systems or alternative traffic signal housingconstructions.

It is an object of this invention to provide an apparatus for generatingand transmitting two different light colors at alternate time periodswithout obtaining an undesirable light reflection from any unlit lightsource in the apparatus.

Another object of this invention is to provide an apparatus inaccordance with the preceding object in the form of a traffic signalapparatus having at least two light sources of different colors with oneof the light sources being surrounded by a one-way light mirror.

Still another object of this invention is to provide an apparatus inaccordance with the preceding objects which is basically similar toconventional equipment and requires little modification to achieve thedesired effect.

Still another object of this invention is to provide an ap paratus inaccordance with the preceding objects which is highly efflcient anduncomplicated.

SUMMARY OF THE INVENTION An apparatus for generating and transmittingtwo different light colors has a first light source for generating lightrays of a first predetermined color with the light rays having a firstpredetermined wavelength. A second light source is provided forgenerating light rays of a second color different from thefirst-mentioned color. Reflector means act to reflect light originatingfrom both of the light sources to a predetermined area. One-way mirrormeans are positioned about the first light source for reflecting lightrays of the second color impinging thereon generated by the second lightsource while permitting passage of light rays therethrough originatingfrom the first light source.

Preferably the apparatus is a traffic signal apparatus such as aWALK-DON'T WALK sign or other message-carrying sign where one portionthereof such as the WALK portion is formed by a translucent ortransparent front stencil panel in the predetermined area. The lightsources are preferably incandescent light lamps or bulbs, one of whichhas a color coatsuch as an orange color coating surrounded by a secondcoating such as a white coating which acts as a one-way light mirror.Light rays from the first light source passing through the orangecoating are intense enough to pass through the white coating when theorange lamp is lit thus illuminating the message. When the white lamp islit, reflection of light at the white coating over the orange lampcauses reflection of all wavelength light rays striking the whitecoating thus preventing any orange cast on the message.

It is a feature of this invention that the coating or one-way mirrormeans used is inexpensive and uncomplicated. Moreover, existing trafficsignal housings can be easily modified by replacement of colored bulbswith colored bulbs carrying the one-way mirror means or positioning of aseparate one-way mirror means element over the colored bulbs.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects,advantages and features of the present invention will be betterunderstood from the following specification when read in conjunctionwith the accompanying drawings in which:

FIG. 1 is a diagrammatic front view of a traffic signal housing andassociated controller in accordance with the preferred embodiment ofthis invention;

FIG. 2- is a semidiagrammatic front view of elements thereof;

FIG. 3 is a top plan view of the elements of FIG. 2;

FIG. 4 is a cross-sectional view through the center of an elementthereof; and,

FIG. 5 is a semidiagrammatic showing of an alternate embodiment thereof.

DESCRIPTION OF PREFERRED EMBODIMENTS With reference now to the drawings,an improved traffic signal control apparatus is indicated generally at10 in FIG. I and is in the form of a WALK-DONT WALK pedestrian signal.The complete apparatus comprises a housing 11 carrying upper and lowerreflectors such as 12 forming a compartment behind each suitably maskedtransparent stencil panel 13 and 14 having transparent clear portionsdenoting the letters of the DONT and WALK signals, respectively. Withinthe bottom reflector 12 are positioned plural light sources comprisinglamps 15 and 16 of one color and lamp 17 of another color with the lamp17 carrying the improved coating 22 of this invention.

The structural elements of the WALK-DON'T WALK will be briefly describedalthough it should be understood that all elements described are wellknown in the art with the exception of the use of the particular one-waymirror means comprising the coating 22 as will be more fully described.

In accordance with conventional design, the apparatus 10 comprises anouter casing or housing 11 as of metal within which is positioned anupper parabolic plane reflector (not shown) having a front opening areain rectangular form directly behind the rectangular DON'T stencil panel13. Within the upper reflector is a single light source 18 such as anorange color coated incandescent lamp. The lower parabolic reflector 12which is preferably identical to the upper parabolic reflector (notshown) defines a front area adapted to lie directly behind the WALKstencil panel 14. The parabolic reflector 12 has a rear reflectingsurface 20 designed to spread all lightimpinging thereon throughout thearea of the WALK panel 14.

As best shown in FIGS. 2 and 3, mounted within the reflector 12 arethree incandescent lamps with two of the lamps such as 15 and 16 actingas light sources of substantially white light. A tinge of blue can beincorporated as by use of standard lunar white lamps. The third lightsource comprises a Portland orange lamp 17, best shown in FIG. 4, havinga conventional Portland orange ceramic coating 21 and a thin white hightemperature silicone type coating 22 of this invention thereover.

In order to better understand the invention, the operation of aconventional WALK-DON'T WALK signal having lamp 17 of a conventionalPortland orange lamp without the coating 22 of this invention will firstbe described. In such convention WALK-DON'T WALK signals, a conventionalcontroller 23 actuates the single orange lamp 18 in the upper reflectoralong with the orange lamp in the lower reflector at one predeterminedtime period so as to obtain illumination of DON'I" WALK in orange duringone time interval. During a second time interval, the controller acts toturn off the two orange lamps and turn on the two white lamps in thelower reflector 12 causing illumination of only the WALK panel in adifferent color (i.e., white) than the color obtained during the firsttime interval. The lamps can be actuated to flash during the preselectedtime periods if desired, Standard time intervals and time periods ofillumination of the two sets of lamps are commonly used in phase withtraffic stop-go-slow signals through suitable known electrical circuitryat an intersection. The problem is that during the time when the orangelamp 17 is unlit and the white lamps 15 and 16 are lit, light rayspassing from the polychromatic white lamps impinge on the unlit orangebulb 17 as best seen by the arrows indicating light rays in FIG. 3. Theimpinging light rays have all components of the polychromatic lightabsorbed by the orange coating with only orange light of a wavelengthcorresponding to the orange color reflected from the orange lamp toeventually pass out through the WALK panel giving an orange tint to theotherwise white light or forms unexpected orange color spots on themessage panel. This orange tint is undesirable.

The reason for the undesirable reflection is that the color of an objectsuch as the orange coating on the lamp 17 causes it to reflect lightrays of certain wavelength and absorb all other wavelength light rays.Thus, when the orange lamp is illuminated, all wavelength light produceddoes not pass through the orange coating but only orange wavelengthlight passes therethrough and from thence to the WALK sign. On the otherhand, when the white lamps are illuminated since the white lighttransmits a polychromatic, composite beam containing light rays, some ofwhich have wavelengths matching that which would be reflected by theorange bulb, the orange portion of the light from the white lightsources is reflected to the WALK sign while all of the light rays ofother wavelengths than orange light are absorbed by the orange coating.

in the improved apparatus of this invention, all structural parts aspreviously described are used, but the Portland orange lamp 17, whichmay be a conventional 8,000-hour Portland or Pedestrian orange 75-watt,60-volt incandescent lamp having an orange colored ceramic glass enamel21 applied to it, has a translucent white outer layer 22 of a hightemperature silicone coating. The combination of the incandescent lampfilament with the orange ceramic coating 21 and the white siliconecoating 22 preferably conforms to the chromaticity transmissionstandards of the Institute of Trafflc Engineers for colored lenses usedwith a noncolored, incandescent lamp as set forth in its TechnicalReport No. of June 23, I963 Adjustable Face Pedestrian Signal HeadStandards and has no chromatic effect for reflection of external lightimpinging upon it. The resultant thicknesses of layers 21 and 22 inconformance with the above referenced specifications are approximately0.0005 inch and 0.00] inch respectively although the thickness can vary.Lamps and 16 can be lamps having centers preferably spaced 3% inchesfrom the center of lamp 17 when lamps l5 and 16 are conventional8,000-hour lunar or Pedestrian white A2lG 75-watt, l-volt incandescentlamps with a ceramic glass enamel applied to the glass bulb so that thecombination of the incandescent lamp filament with this colored coatingwill conform to the chromaticity standards of the Institute of TrafficEngineers for colored lenses used with a noncolored incandescent lamp asset forth in its Technical Report No. 5 of June 29, 1963 Adjustable FacePedestrian Signal Head Standards. The resultant thickness of this layerin conformance with the above referenced specifications is 0.001 inch.[n this case, when the lamp 17 is illuminated, the light source issufficiently intense to cause orange 'ght to pass out of the lampthrough the white silicone coating. On the other hand, when the lamp 17is unlit, and the light sources 15 and 16 are lit, all light raysimpinging on the white outer coating 22 are reflected outwardly with nolight rays being absorbed and none passing to the orange coating so thatno orange tint is reflected to the WALK sign. White by definition is acolor which reflects all colors. In effect, the coating 22 acts as aone-way light mirror, i.e., all light rays impinging on the coating fromoutside thereof as from the sources 15 and 16 are reflected while lightrays emanating from the light source 17 being of higher intensity thanthe outside light rays impinging on the bulb, do pass through thecoating to the outside. Such light rays are high-intensity orange lightrays. While some cut down in the light output of the light source 17does occur, this cut down is not significant. Similarly, a negligibleportion oflight from the sources 15 and 16 may be absorbed by thecoating 22 or passed therethrough. The spacing of the white lamps fromthe orange lamp and/or the light output intensity of the white lamps ispredetermined to assure reflection of light therefrom by the one-waymirror while permitting passage of light from the orange lamp.Similarly, the specific translucent white layer used and color producinglayer of the light source 17 vary in accordance with known practice solong as the translucent layer allows passage of colored light from thesource yet reflects polychromatic light impinging thereon andoriginating from another source.

In another embodiment of this invention, the translucent white layer 22is eliminated from the bulb 17. Instead of a white layer, the one-waylight mirror of this invention is formed by a filter element such as 30positioned over a bulb 17 not having the coating 22. The filter 30 cancomprise a clear glass bubble having outwardly extending flanges 31 forattachment to the reflector and carrying a coating 22A identical to thecoating 22. In this case, the coating 22A functions as does coating 22.in some cases, element 30 can be an orange colored element having acoating 22A thereon with the bulb 17 being a clear or white bulb.

The one way light mirror of this invention can be formed by a thintranslucent silver layer which allows passage of colored light fromwithin but reflects substantially all light impinging thereon andoriginating from without, i.e., bulbs 15 and 16.

While specific embodiments of the present invention have been shown anddescribed, it should be understood that many variations thereof arepossible. For example, the number of lamps and light colors within areflector such as 12 can vary with more than two colors or light sourcesused, less than three light sources or colors used or more than threelight sources or colors used. Similarly, the specific reflector used canvary greatly as can the structure of the message signal used. Theparticular colors used can vary greatly. In all cases, the light sourceoutside of the one-way mirror means emits polychromatic light with aportion of the rays thereof having a wavelength corresponding to thewavelength of the light rays emitted by the light source within theone-way mirror. The term light source as used herein is meant to includethe lamp filament as well as any covering thereover which alters thecolor of the light produced. Thus, the orange bulb or filter isconsidered part of the light sources noted. The principles of thisinvention are applicable to optical systems wherever light sources oftwo different colors are alternately illuminated within a commonreflector.

What is claimed is:

1. A traffic signal apparatus for generating and transmitting twodifferent light colors, said apparatus comprising,

a first light source for generating light rays of a first predeterminedcolor,

a second light source for generating light rays of a second colordifferent from said first-mentioned color,

means for reflecting light originating from both of said light sourcesto a predetermined area,

and one-way mirror means positioned about said first light source forreflecting light rays from said second light source impinging on saidmeans and generated by said second light source while permitting passageof light rays therethrough originating from said first light source.

2. A traffic signal apparatus in accordance with claim 1 wherein saidfirst light source comprises an incandescent lamp and said one-waymirror means is a thin coating over said lamp.

3. A traffic signal apparatus in accordance with claim 2 and furthercomprising means for activating said first and second light sources atdifferent time periods.

4. A traffic signal apparatus in accordance with claim 2 and furthercomprising a housing surrounding said reflector and said light sources,

said area comprising a means for selectively allowing passage of lightto illuminate a message.

5. A traffic signal apparatus in accordance with claim 4 wherein saidthin coating is white.

6. A traffic signal apparatus in accordance with claim 5 wherein saidthin coating is silver.

7. A traffic signal apparatus in accordance with claim 5 wherein saidfirst light source is an orange-colored incandescent lamp and saidsecond light source is a white incandescent lamp.

8. A traffic signal apparatus in accordance with claim 7 and furthercomprising means for activating said first and second light sources atdifferent time periods,

said message being a WALK indication.

9. A traffic signal apparatus in accordance with claim 1 wherein saidone-way mirror means is formed on an element spaced from said firstlight source.

10. In a traffic signal apparatus having a transparent WALK messagepanel and a DON'T message panel, a reflector behind said WALK panel withsaid reflector carrying a first incandescent light source of one color,and a second incandescent light source of a second color constructed andarranged to emit polychromatic light containing some light rays of awavelength corresponding to the wavelength of light rays produced bysaid first incandescent light source, the improve ment comprising,

said first light source having an outer translucent covering forreflecting light impinging thereon from outside of said light sourcewhile permitting light generated by said first light source to passthrough said translucent covering to said WALK panel.

11. The improvement of claim 9 wherein said first light source is anincandescent lamp having a colored layer under said outer translucentcovering.

1. A traffic signal apparatus for generating and transmitting twodifferent light colors, said apparatus comprising, a first light sourcefor generating light rays of a first predetermined color, a second lightsource for generating light rays of a second color different from saidfirst-mentioned color, means for reflecting light originating from bothof said light sources to a predetermined area, and one-way mirror meanspositioned about said first light source for reflecting light rays fromsaid second light source impinging on said means and generated by saidsecond light source while permitting passage of light rays therethroughoriginating from said first light source.
 2. A traffic signal apparatusin accordance with claim 1 wherein said first light source comprises anincandescent lamp and said one-way mirror means is a thin coating oversaid lamp.
 3. A traffic signal apparatus in accordance with claim 2 andfurther comprising means for activating said first and second lightsources at different time periods.
 4. A traffic signal apparatus inaccordance with claim 2 and further comprising a housing surroundingsaid reflector and said light sources, said area comprising a means forselectively allowing passage of light to illuminate a message.
 5. Atraffic signal apparatus in accordance with claim 4 wherein said thincoating is white.
 6. A traffic signal apparatus in accordance with claim5 wherein said thin coating is silver.
 7. A traffic signal apparatus inaccordance with claim 5 wherein said first light source is anorange-colored incandescent lamp and said second light source is a whiteincandescent lamp.
 8. A traffic signal apparatus in accordance withclaim 7 and further comprising means for activating said first andsecond light sources at different time periods, said message being aWALK indication.
 9. A traffic signal apparatus in accordance with claim1 wherein said one-way mirror means is formed on an element spaced fromsaid first light source.
 10. In a traffic signal apparatus having atransparent WALK message panel and a DON''T message panel, a reflectorbehind said WALK panel with said reflector carrying a first incandescentlight source of one color, and a second incandescent light source of asecond color constructed and arranged to emit polychromatic lightcontaining some light rays of a wavelength corresponding to thewavelength of light rays produced by said first incandescent lightsource, the improvement comprising, said first light source having anouter translucent covering for reflecting light impinging thereon fromoutside of said light source while permitting light generated by saidfirst light source to pass through said translucent covering to saidWALK panel.
 11. The improvement of claim 9 wherein said first lightsource is an incandescent lamp having a colored layer under said outertranslucent covering.